Black Tooth Laser on BuildYourCNC

[Tim Fitz]

Hey everyone. I am looking at buying a small 40W laser for mostly hobby stuff but I also have an opportunity to cut parts for a local company to help fund my purchase. Since I can't guarantee any commercial business for my laser I don't want to make a huge investment, but I want a laser that will cut high quality parts. The local company has several part configurations and all have tolerances of +/- 0.001" and edge quality is key for them - no sawtooth edges on the parts which are round. There are also holes in the parts (which are cut from a polyurethane impregnated felt attached to a mylar carrier with a PSA laminated to the back) which can be as small as 0.015". Their biggest complaints about the parts they buy now are scorching of the PSA liner, debris in the holes, melted edges, and sawtooth edges. The largest part is approximately 8" diameter, but I want a table that is at least 12"x24" and preferably 18"x24".

I have read several posts on the chinese lasers, and they are definitely in my price range but I am a bit gun-shy at pulling the trigger on an import when I am not sure who I am dealing with. This brings me to the title of my post. I have seen a DIY laser on BuildYourCNC.com and wanted to know if anyone on here has any experience or opinion on that laser? I know that I can get a chinese laser for not much more, but by building it myself I will know how to maintain it. The drawback is that it has no software for using it like a printer.

Anyway, if someone has experience with the black tooth I'd love to hear it. Also, if anyone has a contact or reliable source for a chinese laser I'd love that info too.

Thanks,
Tim

[Rodne Gold]

Dont base your purchase on getting the business cutting those parts..unlikely you will have success with a cheap laser bearing in mind their demands and most IMPORTANTLY , dont buy ANY laser advertised with the word "hobby" in it.
You will have to spend $3-4k all in if importing a decent small 400x 600mm 60w chinese laser...
Mounting a laser on a machine that was not designed for it , like a small CNC router is an option , so long as you realise that engraving with one will be painfully slow , tho cutting might be ok...

[Scott Shepherd]

You didn't mention the material thickness (or maybe I missed it). If you plan on cutting things more than 1/32" thick (roughly guessing), +/-.001" is going to be impossible. The beam is shaped like an hourglass. The edges will be tapered more than .001" from top to bottom. You might repeatedly cut the same size parts, but if they are that critical on the side, and it's got any thickness to it, you're not going to make that happen, in my opinion. Chinese, hobby, mainstream, professional, none of them.

We do a lot of "precision" parts out of acrylic. They all have tapered holes and tapered edges to some degree.

[Tim Fitz]

You didn't mention the material thickness (or maybe I missed it). If you plan on cutting things more than 1/32" thick (roughly guessing), +/-.001" is going to be impossible. The beam is shaped like an hourglass. The edges will be tapered more than .001" from top to bottom. You might repeatedly cut the same size parts, but if they are that critical on the side, and it's got any thickness to it, you're not going to make that happen, in my opinion. Chinese, hobby, mainstream, professional, none of them.

We do a lot of "precision" parts out of acrylic. They all have tapered holes and tapered edges to some degree.

Thanks for the feedback. The material "sandwich" is approximately 1/16" thick. I have seen samples of the parts, and they are currently being cut successfully by laser. The problem that they are having is that they have 2 current laser shops cutting them. One of the shops always produces top quality parts, but the pricing per part eats all of the margin. The second supplier is much cheaper per part, but the quality is hit and miss. Sometimes they are as good as supplier 1, sometimes the parts have a 50% reject rate. The samples I have seen do have a slight taper on the edge which is acceptable as long as the holes are in the correct locations (GDT speaking) and that the hole opening is within tolerance and free of debris. They did do some testing with ULS at their lab and found that the 40W laser was actually the best option since the tolerances are dictating the cutting speed and not laser power. Also, the higher power lasers tended to score the release liner more than the 40W.

[Scott Shepherd]

Thanks for the feedback. The material "sandwich" is approximately 1/16" thick. I have seen samples of the parts, and they are currently being cut successfully by laser. The problem that they are having is that they have 2 current laser shops cutting them. One of the shops always produces top quality parts, but the pricing per part eats all of the margin. The second supplier is much cheaper per part, but the quality is hit and miss. Sometimes they are as good as supplier 1, sometimes the parts have a 50% reject rate. The samples I have seen do have a slight taper on the edge which is acceptable as long as the holes are in the correct locations (GDT speaking) and that the hole opening is within tolerance and free of debris. They did do some testing with ULS at their lab and found that the 40W laser was actually the best option since the tolerances are dictating the cutting speed and not laser power. Also, the higher power lasers tended to score the release liner more than the 40W.

High power lasers shouldn't score the release liner any more than a low power. We cut .004" Mylar on a 45W and a 75W. Doesn't matter, just need to get the settings dialed in.

I can't speak for accuracy on Chinese machines, but I have no problems on a Universal or Trotec holding tight tolerances.

[Chuck Stone]

I would also think that with tolerances that tight, one problem that may be beyond
your control is the material consistency. You will probably never get that kind of
tolerance on a consistent basis with wood, for example the material itself is too variable at
that level. You would get relative consistency on large parts, but the variability of
wood grain could rule out small ones and those kind of tolerances. Synthetics might
give you better control, but it still depends on what they are. Testing is definitely in order.
Just a thought..

[Keith Outten]

I doubt that you will find a CNC Router that will be capable of the kind of tolerance you mentioned. CNC Routers have an accumulative error from the motion drive system that puts them out of the picture for this type of work. I would think for that level of precision you would have to move up to a CNC Milling machine.

[Mike Null]

Also, the higher power lasers tended to score the release liner more than the 40W.

This is an incorrect assumption.

[Doug Griffith]

I doubt that you will find a CNC Router that will be capable of the kind of tolerance you mentioned. CNC Routers have an accumulative error from the motion drive system that puts them out of the picture for this type of work. I would think for that level of precision you would have to move up to a CNC Milling machine.

I highly doubt he really needs .001" tolerance. Especially if the work is already being done by laser and they are good with it. There are routers out there that hold tolerance well enough for what he most likely needs. My opinion is that it should be a servo driven, ball-screw machine with a tight spindle. My machine can easily hold pretty tight tolerances but wouldn't be in his budget.